====== caseSerial() ======

''string **caseSerial**()''

The function ''caseSerial()'' returns the value saved in the data record in the variable ''SERIAL''. This is useful, for example, if you would like to show the respondent a personalized link to another questionnaire.

  * If the participant was invited via [[:en:survey:mailing|Mailing]], ''caseSerial()'' returns the personal ID of the participant.
  * If an authorization code was used to begin the questionnaire (either transferred in the [[:en:survey:url|Link]] or entered manually), this will be returned when ''caseSerial()'' is used.
 
**Note:** An authorization code in the link to the questionnaire is saved regardless of whether the the questionnaire can only be accessed with an authorization code, or if it is public. To tranfer an ID that is not an authorization code, it is better to use the reference designed for this purpose.
===== Example =====

**Note:** If you are using mailings, normally the function ''[[:en:create:functions:mailschedule|mailSchedule()]]'' is more effective than the following example. If necessary, read the chapter [[:de:survey:opt-in-live|Multi-Wave Surveys with Self-Selection]].


<code php>
html('
  <p>Please access this
  <a href="http://www.soscisurvey.de/project2/?s='.caseSerial().'">
  questionnaire</a> next week!</p>
');
</code>

The authorization code or the personal ID is also available with the [[:en:create:placeholders|placeholder]] %caseSerial% . The following PHP code has the same purpose a the code above. 

<code php>
html('
  <p>Please access this
  <a href="http://www.soscisurvey.de/project2/?s=%caseSerial%">
  questionnaire</a> next week!</p>
');
</code>